Infection control

Question 1

what are the most common healthcare associated infections?

Answer 1

UTIs
Respiratoey infection
surgical site infections

Question 2

what are the most comon pathogenic microorganisms?

Answer 2

• enterobacteriaceae eg. e.coli
  -staphylococcus aureus
• clostridium difficle

Question 3

what is a reservoir?

Answer 3

• this is a location where pathogens may live and multiply
  eg. in or on a person or animal, in soil, in water

Question 4

what are means of exit from the reservoir?

Answer 4

• ears (wax)
• broken or infected skin
• skin (flakes)
• anus (faeces)
• eyes (tears)
• nose (secretions)
• vagina
• urethra
• seminal vesicles

Question 5

what are contact modes of action?

Answer 5

direct - body surface to body surface between an infected individual and susceptible person
droplet - generated during coughing or sneezing

Question 6

what are non-contact modes of transmission?

Answer 6

• airborne: generation of aerosols which are airborne and can spread considerable distances
• surfaces: infectious agent depostied onto an object or surface and survives long enough to transfer to another person who touches the surface
• vehicle: usually a single contamination source spreads infection eg. Legionella outbreak in Edinburgh 2012 - 4 deaths from contaminated water
• vector borne: transmision by an insect or animal eg. mosquitos

Question 7

what are examples of pathogens transmitted by droplet?

Answer 7

Covid-19
adenovirus
haemophilus influenza B
influenza virus
measles
streptococcus pyogenes

Question 8

what are infection control measures for droplet transmission?

Answer 8

isolation of individual
PPE - face masks

Question 9

what are pathogens that are airborne?

Answer 9

myobacterium tuberculosis
measles
covid19
varicella virus

Question 10

what are routes of entry into the body?

Answer 10

conjunctiva of the eyes
broken skin
insect bites
nose
mouth
anus
penis
vagina

Question 11

what gram postive bacteria can live on surfaces for months

Answer 11

S. aureus (MRSA)
s. pyogenes
enterococcus spp
C. difficle (spores)

Question 12

what gram negative bacteria can live on surfaces for months?

Answer 12

acinetobacter spp.
E. coli
P. aeruginosa
serratia marcescens

Question 13

what gram negative bacteria species can only persist for days

Answer 13

H. influenza
bordetella pertussis
Proteus vulgaris
Vibrio cholera

Question 14

what respiratory viruses can persist for hours?

Answer 14

corona virus
influenza virus
coxsackie virus
SARS virus

Question 15

what blood borne viruses can persist for more than a week?

Answer 15

HIV
CMV
Hepatitis B
Herpes simplex

Question 16

what fungal pathogens persist for many months?

Answer 16

Candida albicans

Question 17

what are common alcohol disenfectants?

Answer 17

ethanol, propanol. isopropyl alcohol
- active against vegatative forms of bacteria, fungi and coated viruses
- limited contact time due to rapid evaporation from surfaces limits antimicrobial activity
- used at 70-90% v/v

Question 18

what are chlorine disenfectants?

Answer 18

• most widely used disenfectants in hospitals and industry
• in aqueous solution hypoclorite ion which is in equilibrium with hypochlorus acid species responsible for antimicrobial activity
• hypoclorus acid is bactericidal, fungicidal and virucidal activity against both coated and uncoated viruses

Question 19

how does pH affect antimicrobial activity in clorine disenfectants?

Answer 19

if pH > 9 the antimicrobial is lowest since the hypochlorite ion prodominates
if pH is < 7 hypochlorus acid prodominates

Question 20

what are iondinated disenfectants?

Answer 20

• iodine has useful bactericidal, fungicidal, sporicidal and virucidal activity
• activity primarly resides with I2
• iodine is used clinically as an iodophor product (iodine carrier/releasing agent)
• povidone - iodine (complexing agent)
• poloxamer-iodine (surfactant solubilser)
• mainly used as a skin disenfectant eg. pre-surgey

Question 21

what are examples of peroxygens?

Answer 21

• hydrogen peroxide (inactivated by organic matter)
  -peracetic acid (not inactivated by organic matter)
• both agents kill bacteria, fungi and viruses
• peracetic acid is also sporocidal
• exert antimicrobial activ ity through generation of hydroxyl free radicals

Question 22

what are quaternary ammonium compounds?

Answer 22

• benzalkonium chloride
• cetrimide
• cetylpyridinium chloride

the QACS adsorb and penetrate cytoplasmic membrane
- loss of membrane integrity and escape of intracellular contents
- loss of membrane bound enzyme function

Question 23

what are factors that place a person at risk of infection?

Answer 23

• age
• immune status
• genetic
• concurrent co-morbidities
• nutritional status
• behaviours

Question 24

what are possible interventions to prevent infection?

Answer 24

vaccination

clinical intervention in diseases:
- diabetes (glucose control)
- COPD (cessation of smoking)
- Malnutrition (appropriate nutritional support)